The present invention relates to a feed-through type multilayer capacitor having a through electrode and an earth electrode on the outer surfaces of dielectric sheets to be laminated to form one block of layered structure.
As shown in a perspective view, a longitudinally sectional view and an exploded perspective view of FIG. 1, FIG. 2 and FIG. 3, respectively, a conventional feed-through type multilayer capacitor has been constructed by laminating a first dielectric sheet 2 provided with a through electrode 1 thereon, a pair of second dielectric sheets 4, 6 provided with earth electrodes 3, 5 thereon, and an insulating sheet 7; and providing terminals 9, 10, 11 for the electrodes 1, 3, 5 on the outer surface of the sheets; thereby forming one block 8 of square pillar type having approximately constant dimensions. The pair of second dielectric sheets 4, 6 is laminated on the top and bottom faces of the first dielectric sheet 2 respectively such that the earth electrodes 3, 5 are placed traversely in a direction orthogonal to the line of the through electrode 1, and the insulating sheet 7 is mounted on the top face of the second dielectric sheet 4. Accordingly, sheets 7, 4, 2, 6 are laminated in that
order to form a feed-through type multilayer capacitor comprising one block 8 providing with a pair of through electrode terminals 9, 10 of cover type connected with the through electrode 1 on opposite sides of the block 8 and an earth electrode terminal 11 connected with a pair of earth electrodes 3, 5, the terminal 11 having the form of a ring around the intermediate portion of the block 8. Thus, an electrostatic capacitance is provided between the through electrode 1 and earth electrodes 3, 5, which are arranged transverse to each other and sandwich the corresponding dielectric sheet 4 or 2 therebetween in the direction of thickness. Both ends of the through electrode 1 are respectively drawn out to the through electrode terminals 9, 10 formed on both the end faces of the block 8 of the dielectric sheets 2, 4, 6 and the insulating sheet 7. The earth electrodes 3, 5 are drawn out to the earth electrode terminal 11 formed between these through electrode terminals 9, 10. The electrostatic capacitance is formed between the earth electrodes 3, 5 and a crossing portion 12 of the through electrode 1 disposed between the earth electrodes 3, 5.
In a feed-through type multilayer capacitor of such construction as described hereinabove, the thickness of the through electrode 1 is normally as extremely thin as several .mu.m and the resistance value R of the through electrode 1 connected between the through electrode terminals 9 and 10 becomes high. Therefore, when the energizing current of the through electrode 1 becomes large, the through electrode 1 is heated and becomes high enough to melt the solder, which is used to solder the through electrode terminals 9, 10 of the feed-through type multilayer capacitor and the earth electrode terminal 11 thereof, to the patterns of the printed circuit board (not shown). The repeated heating operation causes stress among the through electrode terminals 9, 10, the earth electrode terminal 11 and the other portions so as to cause cracks in the dielectric sheets 2, 4, 6 or the insulating sheets 7.